package com.openyelp.apps;

import java.math.BigInteger;  
import java.util.Date;  
import java.util.Random;  
import java.util.zip.CRC32;  
  
public class keygen  
{  
  /** 
  * @param s 
  * @param i 
  * @param bytes 
  * @return 
  */  
  public static short getCRC(String s, int i, byte bytes[])  
  {  
      CRC32 crc32 = new CRC32();  
      if (s != null)  
      {  
          for (int j = 0; j < s.length(); j++)  
          {  
              char c = s.charAt(j);  
              crc32.update(c);  
          }  
      }  
      crc32.update(i);  
      crc32.update(i >> 8);  
      crc32.update(i >> 16);  
      crc32.update(i >> 24);  
      for (int k = 0; k < bytes.length - 2; k++)  
      {  
          byte byte0 = bytes[k];  
          crc32.update(byte0);  
      }  
      return (short) (int) crc32.getValue();  
  }  
  
  /** 
  * @param biginteger 
  * @return String 
  */  
  public static String encodeGroups(BigInteger biginteger)  
  {  
      BigInteger beginner1 = BigInteger.valueOf(0x39aa400L);  
      StringBuilder sb = new StringBuilder();  
      for (int i = 0; biginteger.compareTo(BigInteger.ZERO) != 0; i++)  
      {  
          int j = biginteger.mod(beginner1).intValue();  
          String s1 = encodeGroup(j);  
          if (i > 0)  
          {  
              sb.append("-");  
          }  
          sb.append(s1);  
          biginteger = biginteger.divide(beginner1);  
      }  
      return sb.toString();  
  }  
  
  /** 
  * @param i 
  * @return 
  */  
  public static String encodeGroup(int i)  
  {  
      StringBuilder sb = new StringBuilder();  
      for (int j = 0; j < 5; j++)  
      {  
          int k = i % 36;  
          char c;  
          if (k < 10)  
          {  
              c = (char) (48 + k);  
          }  
          else  
          {  
              c = (char) ((65 + k) - 10);  
          }  
          sb.append(c);  
          i /= 36;  
      }  
      return sb.toString();  
  }  
  
  /** 
  * @param name 
  * @param days 
  * @param id 
  * @param prtype 
  * @return 
  */  
  public static String MakeKey(String name, int days, int id)  
  {  
      id %= 100000;  
      byte bkey[] = new byte[12];  
      bkey[0] = (byte) 1; // Product type: IntelliJ IDEA is 1  
      bkey[1] = 14; // version  
      Date d = new Date();  
      long ld = (d.getTime() >> 16);  
      bkey[2] = (byte) (ld & 255);  
      bkey[3] = (byte) ((ld >> 8) & 255);  
      bkey[4] = (byte) ((ld >> 16) & 255);  
      bkey[5] = (byte) ((ld >> 24) & 255);  
      days &= 0xffff;  
      bkey[6] = (byte) (days & 255);  
      bkey[7] = (byte) ((days >> 8) & 255);  
      bkey[8] = 105;  
      bkey[9] = -59;  
      bkey[10] = 0;  
      bkey[11] = 0;  
      int w = getCRC(name, id % 100000, bkey);  
      bkey[10] = (byte) (w & 255);  
      bkey[11] = (byte) ((w >> 8) & 255);  
      BigInteger pow = new BigInteger("89126272330128007543578052027888001981", 10);  
      BigInteger mod = new BigInteger("86f71688cdd2612ca117d1f54bdae029", 16);  
      BigInteger k0 = new BigInteger(bkey);  
      BigInteger k1 = k0.modPow(pow, mod);  
      String s0 = Integer.toString(id);  
      String sz = "0";  
      while (s0.length() != 5)  
      {  
          s0 = sz.concat(s0);  
      }  
      s0 = s0.concat("-");  
      String s1 = encodeGroups(k1);  
      s0 = s0.concat(s1);  
      return s0;  
  }  
  
  public static void main(String[] args)  
  {  
      Random r = new Random();  
      System.out.println(MakeKey("young", 0, r.nextInt(100000)));  
  }  
}  